Replaces the SGLang placeholder with a full serving recipe, mirroring the vLLM section's structure.
- `sglang serve` launch command with `--tool-call-parser poolside_v1` and `--reasoning-parser poolside_v1` (both registered in SGLang)
- Notes that Laguna support landed via sgl-project/sglang#24204 (shared with Laguna XS.2) and is currently on SGLang main; install-from-source instructions are included accordingly
- Points to the FP8/NVFP4 checkpoints (auto-detected via `quantization_config`) and the SGLang Cookbook for the shared Laguna implementation path
